Finding correct Product key from WIndows 10 computers

How do I find the right product key from Windows 10 computers.

I tried running nrisoft, Belrac and magic jelly bean and looks like they are pulling same product key on all 5 laptops in our company. How is that possible ? Is it because may be these computers were upgraded to Windows 10 at some point from Windows 8 and therefore showing the same key on all computers that I am trying to recover ?
These laptops were purchased from retail in the past 4 years so most likely had windows 8 on them.

How can I find the OEM key that was shipped with the computer if there is physically no sticker on it. I have to fill out MS audit report and therefore its kind of important I find the right info.

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@Chirag your code as posted here doesn't work as there's a blank line at #3 which has crept in as part of the cut & paste. However it doesn't really help as it gets the DigitalProductId value from the registry and decrypts it. Nick is already getting that from the keyfinders he's using.

Since Windows 8 OEM activation of operating systems has used a hardware embedded key injected into the system BIOS. The same system is used in Windows 10 but additionally, since build 1511, a digital license (called "digital entitlement" in Windows 10) which is a method of activation in Windows 10 that doesn't require you to enter a product key has been used. If you upgraded to Windows 10 for free from an activated copy of Windows 7 or Windows 8.1, you should have a digital license instead of a product key.

Because the system Registry has a legacy location at HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\DigitalProductId that needs to be populated when Windows is activated, commonly a "placeholder" key is inserted at activation and this is identical (certainly between system builders). This is the value Nick is retrieving.

If the machines still have an OEM install then use the Powershell script above. If you've re-imaged them then you should be using VAMT for your audit evidence.